Self-cleaning oven having cooling and ventilating system



w13,s4s,152

passageway surroundpassageway is of sufficient one provide sufficient air cirg oven characterized by having g even during the self-cleaning spension means effecting minimal and minimal interference with alleviating means for cir- -fi1led air from within the y oxidizing the smoke-partiperature reaction products with and a door having a flow of air r insulated portion and between 9/1969 Torrey et a1. 11/1969 Torrey et a1.

Primary Examiner-Volodymyr Y. Mayewsky AttorneyWofford and Felsman ABSTRACT: A self-cleanin sufficient cooling through thermal currents alone and without the use of a fan. The oven has an inner insulated tub suspended within a cabinet with an air ing the insulated tub. The air thickness that thermal currents a1 culation to prevent over heatin cycle. Also disclosed are su transfer of heat by conduction the flow of thermal currents; smokeculating the high temperature, smoke insulated tub while simultaneousl cles and mixing the high tern the air of the thennal currents over the insulated tub before being vented into the room;

between a baffle and an inne 'liHiiii' rziiiii/oi; A2 lb 1/26 Glen W. Klepzig Abbeville, Miss. [21] Appl. No. 805,582

Mar. 10,1969 1451 Patented Dec. 15, 1970 Chambers Corporation Cleburne, Tex.

VENTILATING SYSTEM 7 Claims, ZDrawing Figs.

References Cited UNITED STATES PATENTS 3,310,046 3/1967 Scott et 5/1968 Rawald et a1.

O United States Patent [72] lnventor [22] Filed [73] Assignee [54} SELF-CLEANING OVEN HAVING COOLING AND [50] Field PATENTED um 5 I970 3.548; 152

INVENTOR ATTORNEYS 1 sets-CLEANING. OVEN HAVING-COOLING AND 'YENTILATING SYSTEM BACKGROUND OF THE INVENTION l. Field of the lnvention ,Zlhis invention relates to ovens used in family dwellings; and more particularly, to so-called self-cleaning ovens.

2. Description of the Prior Art Cleaning ovens with their baked-on deposits has long been an onerous chore for the housewife It is known to employ ovens, commonly referred to' as self-cleaning ovens, that raise their interior surfaces, including any unsightly {deposits thereon, to temperatures of from about 875* to 900 F. At this temperature most of the deposits are oxidized or burned to smoke particles. The smoke particles arejn turn oxidized to gaseous reaction products. One of the major problems in manufacturing and installing these selflcleaning ovens has been the achieving of sufficient inner dimensions of the ovens,

while providing sufficient cooling of the outer surfaces to prevent damaging the structure and accoutrements thereabout. The problem is particularly acute in built-in, selfcleaning ovens in which the self-cleaning oven is built into a standard cut away structure of the home instead of in a selfstanding range. Ordinarily, the structuresubject to overheating is a wooden frame in a home andthe accoutrements are the wiring, accessories, and control panel. To efiect the desired degree of cooling, conventional units have employed a fan to achieve a forced circulation of air through small dimension air passageways about theinner insulated tub; and have employed suspending means such as angle iron that interrupts the smooth flow of cooling air and simultaneously conducts large amounts of heat from the oven to the surrounding structure. The self-cleaning. ovens of the prior have not been altogether satisfactory in that they are more expensive and more cumbersome to install; provide the objection of the fan blowing during the self-cleaning cycle; and overheat the surround ing structure if the fan burns out during the-self-cleaning cycle.

BRIEF DESCRIPTION OF THE orutwrNo FIG. 1 is a cross-sectional view from the side of one embodiment of the invention. I v

FIG. 2 is a cross-sectional view from the front taken along lines ll-ll of FIG. 1..

DESCRlPTlON or PREFERRED EMBODIMENT. 1

In FIG. 1 there is shown a side view incross section of a selfcleaning oven in accordance with a preferred embodiment of the present invention. Oven 11 has an innerinsulated tub 13, an outer cabinet 15 and-a door 17.

Inner insulated tub 13 has an inner liner l9, lation 21 and an outer insulation retainer 23.

Door 17 is positioned at the entrance and front of the insulated tub and has an inner insulated portion 25 having an inner layer 27, a layer of insulation 29 and an outer insulation retainer 31. Door 17 also has a front panel 33 that is a layer of insufrequently of a design or material that is adversely affected by high temperatures. Panel 33 is disposed-near but spaced from 1 inner insulated portion 25. To further protect panel 33 from elevated temperatures,- a baffle plate -35 is disposed intermediate the inner liner face of the front panel and the outer insulation retainer of the inner insulated portion, and air circulation passageways 37 and 39 are provided .on each side of battle la a particularly preferred embodiment, the :oven employs a door like the one described in my copending' application, Ser.

ing of structure and accoutrements in the vicinity of the oven.

Expressed otherwise, the air passageway has a minimum cross section thickness of at least one-half inch in order that thermal currents will circulate sufiicient air. An inch or .more in thickness is even better although in conventional built-in structures it is rarely possible to obtain an inch'thickness of air passageway at the rear of the oven and still provide sufficient thickness of insulation 21 and wiring baffle 47 at the rear of the oven.

Wiring baffle 47 provides a convenient space facilitating grouping of wiring from power source'and controls. Wiring baffle 47 has louvers 49 for providing air circulation to help keep the wiring and accessories therein cooler.

Suspension means is provided for suspending insulated tub 13 within outer cabinet 15. To keep the heat transferred from the insulated tub to the surrounding cabinet and structure to a minimum, the suspension means must effect minimal transfer of heat by conduction, and to maintain'adequate cooling must effect minimal interference with the flow of thermal currents about the inner insulated tub. As a par't'of the suspension means, a plurality of small area contactsconnect two sides of the insulated tub with the cabinet; By plurality of small area contacts is meant at least two contacts-between insulated tub -l3 and cabinet'lS. The contacts have asmall cross-sectional area through which to transfer heat by conduction and have a small external area to provide very little interference with the flow of thermal currents of air up the side of insulated tub 13. It has been found that excellent suspension, meeting the above requirements, is provided by four embossed protrusions 51,

FIG. 2, extending outward from outer. insulation retainer 23 and connected with cabinet 15. Protrusions'Sl may be connected by frictional force; for example, held in respective niches formed in the side of cabinetlS. Preferably, however,

- are very narrow and have very little cross-sectional areato No. 709,978, filed Mar. 4, I968 now US. Pat. No. 3,453,997 Y entitled OVEN DOOR embodied by reference herein.

Outer cabinet 43, illustrated in more detail in FIG. 2,.sur-

rounds insulated tub l3. Cabinet 43 defines an air passageway 45 about insulated tub 13.Air passageway 45 is of sufficient transfer heat by conduction. Moreover, supports 53 are readily cooled by the cool, incoming air traveling along the bottom air passageway 45.

A smoke-alleviating means is provided for circulating the .high temperature, smoke-filled air within-theinsulated tubto the top of the tub where the smoke particles are further oxidized, preferably to products of combusti'oriysuch as, carbon dioxide; and conveying the resulting high' temperature gases including reaction products, into admixture with the air circu lated'through air passageway 45 by the thermal currents for cooling in the air passageway over the insulated tub before being vented into a room. I

As indicated hereinbefore, the air within the oven is heated to a temperature of from 875 to 900 F., creating smoke-filled air. To allow this air to be carried outside the oven and prevent redeposition of material on the oven upon cooling, receptacle 55 penetrates through the top of the insulated tub. Receptacle 55 contains a catalytic filter, 57.which catalyzes the oxidation of the smoke particles. A supplemental heater element 59'heats the catalytic filter above at least 500 F. and also heats the smoke particles to facilitate the oxidation thereof. Conduit means is provided to conduct the hot oxidation, or reaction, products and the high temperature air toward the front of the insulated tub. Suitable-conduitmeans comprises vertical standpipe 61 having symmetrical conduits 63 teed thereinto. Conduits 63 also extends toward the front of the oven to form a U-shaped conduit which ultimately admixes the hot gases with the air of the thermal currents flowing through air passageway. 45 over inner insulated tub 13. The resulting admixture rapidly cools the hot gases, which may be as high as 700 at the outlet of conduit 63, to a temperature-of less than 300 while still within top vent 65. Ordinarily, temperature of the air in top air passageway will be about 120 maximum and cools top vent 65 as well asfurther admixing with the high temperature gases from conduit 63. Temperatures are in degrees Fahrenheit.

A gapis provided at the bottom center of door stop 67 which normally seals the door with the front of the insulated tub, to allow circulation of air past bake element 69 and into the oven. Door stop 67 may be on the door or the insulated tub. This provides circulation in order to pass the high temperature, smoke-filled air within the insulated tub past catalytic filter 57 and into admixture with'the air of the thermal currents passing around the insulated tub.

For heating the interior of the oven to this elevated temperature during the self-cleaning cycle, there are four heating elements. One of the heating elements, a supplemental heating element 59, has been described. Bake element 69 has been referred to. In addition, there are broil elements 71 and a mu]- lion element 73. The bake and the broil elements are conventional and need not be described herein. Ordinarily, they operate on 220 volts in conjunction with a thermostat control. The mullion element is provided to compensate for heat loss around the oven door at the elevated temperature of the selfcleaning cycle. Ordinarily, the heating elements operate on a reduced voltage; such as, 110 volts; during the self-cleaning cycle to effect the high temperature inside the oven without consuming excessive power. Moreover, no elaborate controls are required to prevent the elements burning out under this reduced potential.

Wiring compartment 75 and instrument panel 77 are illustrated at the top of oven 11. Top vent 65 serves to direct the heated effluent air out into the room and past panel 77. Moreover, louvers 79 are provided at the back of wiring compartment 7 to circulate air therethrough and out opening 81, .to further cool wiring compartment 75.

In operation, the oven is switched to the self-cleaning cycle. The elements begin to heat. As indicated before, the oven and elements are designed such that temperature of from 875 to 900 F. is attained within the oven in about one hours time. The oven is retained at a temperature of about 900 F. foran hour and about 1 hour is required for cool down. Air circulation through the oven is provided through the gap at bottom center of door stop 67 such that the contaminants deposited on the interior components of the oven are oxidized away and the hot gases passed into admixture with the air being circulated by thermal currents about the insulated tub and, thence, into the room. if desired, a vent pipe can be employed to vent the high temperature gases and the air circulated by the thermal currents outside the home. Such a vent pipe is ordinarily unnecessary.

On the other hand, cooling air circulation around the exterior of the insulated tub is effected by thermal currents. The thermal currents provide a means for automatically effecting the requisite flow of air about the outer insulation retainer of the insulated tub. Specifically, as the heat penetrates through insulation 21 and the temperature of insulation retainer 23 increases, increasing thermal currents are effected about the sides and rear of the tub. The increased thermal currents accordingly draw more air into the bottom air passageway 45 and an increased flow of air results through top air passageway 45 and out the exit vent 65.

One of the particular advantages of the oven of the invention is that, despite the fact that no fan or supplemental source of cooling is provided, the materials ordinarily employed in manufacturing self-cleaning ovens are adequate and no exotic materials are necessary. For example, the inner liner 19 is made, of the usual materials of construction; such as, stainless steel or steel covered by a layer of ceramic or other high temperature enamel. The outer insulation retainer is ordinarily of metal such as conventionally employed in self-cleaning ovens. Insulation 21 is the insulation conventionally employed in such ovens; for example, high density mineral wool.

Enlarged air passageways are provided at the bottom and at the top of the insulated tub in order that there be no restriction of flow of air in these regions, the only restriction being that due to the necessarily reduced passageways at the side and rear of the insulated tub.

The invention has been described with respect to built-in ovens since it is in this area that the problem is most critical.

The self-cleaning ovens of the invention may be equally advantageously employed, however, in free standing ranges and alleviate the need for circulating means for circulating cooling air past the exterior of the insulated tub.

Although the invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

lclaim:

1. A self-cleaning oven of the type having heating element provisions for both cooking and cleaning comprising:

a. an inner insulated tub having an inner metallic liner, a

layer of thermal insulation and an outer metallic insulation retainer; electrical heating element means positioned in said tub and having cooking and high temperature cleaning portions;

b. a door positioned at the front and entrance to said insulated tub and having an inner insulated portion having an inner metallic liner, a layer of thermal insulation and an outer metallic insulation retainer; a front panel connected with said inner insulated portion but spaced from said outer insulation retainer of said'door;and a metal baffle plate disposed intermediate said front panel and said outer insulation retainer of said inner insulated portion;

c. an outer metallic cabinet surrounding said insulated tub and defining an air passageway thereabout of sufficient thickness that thermal currents alone will circulate sufficient air to prevent overheating of a structure and accoutrements in the vicinity of said 1 oven said air passageway having inlets and outlets;

d. suspension means suspending said insulated tub within said cabinet, effecting minimal transfer of heat by conduction and minimal interference with flow of said thermal currents, and consisting essentially of a plurality of small area contacts connecting two sides of said insulated tub with said cabinet; and

e. smoke-alleviating means for circulating high temperature, smoke-filled air within said insulated tub to the top of said tub, oxidizing the smoke particles, and conveying the high temperature gases into admixture with the air circulated by said thermal currents for cooling in the top air passageway over said insulated tub and before being vented into a room through said outlets.

2. The oven of claim 1 wherein said plurality of small area contacts comprise embossed protrusions in said outer insulation retainer of said insulated tub.

3. The oven of claim 2 wherein said embossed protrusions are fastened to said cabinet with sheet metal screws.

4. The oven of claim 1 wherein said suspension means also comprise a plurality of supports of small cross section connecting the bottom of said insulated tub with said cabinet.

5. The tub of claim 1 wherein said air passageway has a minimum thickness of at least one-half inch.

6. The oven of claim 1 wherein enlarged .air passageways are provided at the top and bottom of said insulated tub.

7. The oven of claim 1 wherein said door has means providing closures at the side of the space between said baffle plate and said outer insulation retainer; meansproviding openings at the top and bottom of said space between said baffle plate 1 and said outer insulation retainer; and means providing a recessed portion in said outer insulation retainer of said inner insulated portion, whereby'air entering bottom of said space subjected to a draw action. 

